As information-based industries constitute an ever growing part of national economies in many developed as well as developing countries, telecommunication networks have become an essential part of national infrastructure. Especially in developed economies, industries as well as societies are highly dependent on faster and easier access to information, entertainment, and education via the telecommunications networks.
In recent years, use of mobile communications devices for voice telephone services, email or text messaging services and even multi-media service has become commonplace, among mobile professionals and throughout the more general consumer population. Mobile service provided through public cellular or PCS (personal communication service) type networks, particularly for voice telephone service, has become virtually ubiquitous across much of the world. In addition to public networks, similar wireless technologies have provided relatively small scale networks for enterprise applications, typically offering wireless service analogous to private branch exchange (PBX) type service. Such a smaller scale private system includes several base stations, similar to but scaled down from those used in the public networks, in combination with a private circuit switch or more recently an Internet Protocol (IP) router or network, for providing communications between devices and with external networks. Although sometimes referred to as an “indoor cellular network” or “indoor system,” such enterprise systems need not be literally indoors and for example may offer coverage across an entire campus area. Alternatively, such an enterprise cellular communication system may be referred to as a “pico-cell” system, with the outdoor public cellular communication system covering a wider area being referred to as a “macro-cell” system.
As broadband IP connectivity to homes and offices has become more common, and the speeds of packet-switched communications equipment and the speed of processors have increased, a variety of applications have emerged that utilize IP packet transport as an alternative bearer for voice communications. As an extension of these developments/deployments into the customer premises, particularly for residential or small business applications, equipment manufacturers have recently begun offering “femto” cell devices, e.g., for home installation. A “femto” cell system is a base transceiver system (BTS) forming a compact base station. In most recent examples, such compact base stations are equipped with VoIP capability and an IP interface, for example, connecting through a digital subscriber line (DSL) modem or to a cable modem to a wireless carrier network. One such unit in a home or small business, for example, would allow mobile station users in the premises to make and receive calls via the existing broadband wireline service from the customer's Internet Service Provider (ISP), without consuming air-time minutes for wireless service that otherwise would connect directly to a wireless carrier network.
Typical femto nodes are deployed in the owned licensed spectrum of a telecommunication service provider's (carrier). This allows the carrier to manage any radio frequency (RF) interference with other communication channels. In such an installation of the femto nodes, communication from the femto node is tied to such carrier's mobile network, meaning that all calls and connections originating from and destined to the femto cell are tied to such carrier's mobile switching center (MSC).
FIG. 1 illustrates a simplified diagram of the environment of a typical femto/macro cell (referred to hereinafter as femto cell) 10 architecture. Typical femto cells are low-power wireless access points that operate in licensed spectrum to connect standard mobile devices to a mobile operator's network using residential DSL or cable broadband connections. The femto cell 10 may be implemented in a home 12 using an integrated cellular base station and DSL modem, seen in FIG. 1 as a single-unit access point 14. In alternate embodiments, the access point 14 may include a cable modem, an optical modem, etc. The access point 14 may be connected to a femto cell gateway 16, which connects the access point 14 to an external communications network 18. The femto cell 10 illustrated herein may be operated by a mobile service provider that operates a macrocell base transceiver system (BTS) 20 via a radio network controller 22.
FIG. 2 illustrates a prior art implementation of a femto cell access point 50 (also referred to in the art as femto cell node), which may provide the function of the femto cell access point 14 seen in FIG. 1. The femto cell access point 50 converts a digital data stream into an RF signal, and vice versa. The femto cell access point 50 may be connected to a digital broadband link 52 such as a DSL line, a cable, etc., via a DSL or other broadband modem (not shown). A mixed signal front-end baseband transceiver 54 may be used to convert the broadband digital signal into analog baseband signal and vice versa. The baseband transmitter 54 is bi-directionally interconnected to an integrated radio transceiver 56 containing programmable frequency synthesizers for generation of transmit and receive local oscillator signals, and other necessary components such as loop filters, etc. The integrated radio transceiver 56 communicates via filters 60 and linear amplifiers 58 to a duplexer 62 connected to an RF antenna 64. The RF antenna 64 receives and transmits signals in order to communicate with mobile devices.
Because the femto cell 10 operates in the licensed spectrum of the mobile service provider, such mobile service provider monitors the usage of the femto cell 10. Additionally, the mobile service provider may set-up the femto cell in a manner so that the traffic generated by the femto cell 10 is billed by the mobile service provider in some manner, which may be different than billed traffic passing directly between mobile users and traditional cell cites. However, such deployment of femto cells in mobile service providers' licensed spectrum restricts the use of the femto cells to the mobile service provider. Moreover, generally, the mobile service provider may restrict the use of the femto cells to only those mobile devices that are capable of communicating over the licensed spectrum of such mobile service provider. Therefore, there is a need for an alternate architecture of femto cells that makes the use of such femto cells more flexible and universal.